Pump Plungers and Methods

ABSTRACT

Various embodiments of the invention provide pumps, plungers and plunger assemblies, as well as methods of using them. In accordance with some embodiments, a plunger may comprise a ceramic material and/or may have a facial profile that may allow for more efficient pumping operations. In particular embodiments, for example, a plunger may have a facial profile that allows for deformation of at least a portion of the plunger when the face of the plunger is in contact with a pressurized fluid. Other embodiments provide plunger assemblies, which may comprise a flexible coupling attachment. Yet other embodiments provide pumps comprising such plungers and/or plunger assemblies.

This application is a continuation of U.S. patent application Ser. No.10/883,012 filed Jun. 30, 2004 by J. Mark Chenoweth and entitled “PumpPlungers and Methods” (the “'012 application”), which is acontinuation-in-part of U.S. patent application Ser. No. 10/422,059filed Apr. 22, 2003 by J. Mark Chenoweth and entitled “Pump with CeramicSeal and Methods for Producing,” which has been granted as U.S. Pat. No.7,134,851, the entire disclosures of which are incorporated herein byreference for all purposes.

BACKGROUND OF THE INVENTION Background of the Invention

The present invention relates generally to pumps and specifically tocomponents for pumps.

Those skilled in the art will ascertain that pumps generally, andplunger pumps in particular, depend on effective sealing to preventexcessive leakage through the gap between a plunger and any sealingmember around the plunger. Without proper sealing, the material beingpumped can tend to evacuate the pump chamber along the length of theplunger, instead of through the designed exit port. This leakage notonly can reduce the efficiency of the pump, it can create maintenanceissues and waste a fairly significant amount of the material beingpumped. In fact, significant leakage can sometimes even prevent theoperation of the pump itself. Hence, in the past, and in particular withplunger pumps, a variety of packing and/or sealing materials, includingPolytetrafluoroethylene (“PTFE”), perfluoroelastomers (including, forexample those commercially available from DuPont Dow Elastomers L.L.C.™under the trade name KALREZ™), and various other polymers, plastics andthe like have been used as sealing members to surround the plunger andprevent leakage of the fluid along the plunger.

Unfortunately, however, in order to adequately seal the plunger fromleakage, such packing materials usually must maintain contact with theplunger as it moves reciprocally. The packing materials, therefore, tendto degrade relatively quickly (due at least in part to friction betweenthe plunger, the packing material and/or the fluids being pumped, aswell as the expendable nature of the packing materials themselves),allowing progressively more leakage over time. Moreover, as the packingmaterials degrade, there is a tendency by users to tighten the fittingon such pumps periodically, compressing the packing materials to preventthis progressive leakage, which can significantly impact the efficiencyof the pump and require more power for operation. Furthermore, overtime, the packing materials can, in fact, score the plunger itself,requiring replacement of the plunger, which can be costly and timeconsuming. This problem, which can be mitigated, but generally noteliminated, by the use of lubricants to reduce friction, is exacerbatedby the fact that such pumps often are used in relatively remotelocations because of their desirability as being self-powered, such thatthey can run unattended for relatively long periods of time. Moreover,the use of lubricants imposes additional maintenance overhead andexpense, and it presents the danger that the lubricant might contaminatethe material being pumped.

As disclosed in the '059 application, many of these issues can beaddressed by using a ceramic or similar material for the pump plungerand/or the sealing member surrounding the plunger. Moreover, theapplicant has discovered that, by varying various properties of theplunger, additional benefits may be obtained.

Those skilled in the art will also appreciate that there must be someway to communicate the reciprocal driving force of a driving mechanism,such as a motor, etc., to a plunger, in order to reciprocally drive theplunger and thereby effect a pumping operation. In the past, a thrustrod or other device was driven by the driving mechanism, and the thrustrod included some sort of hardware designed to connect with a plunger.Examples of such hardware include threaded attachments, collars, cotterpins, bolts and the like. Often, such hardware requires relativelyprecise axial alignment between the thrust rod and the plunger, however,to prevent excessive wear of either component. Moreover, such hardwarecan tend to impose excessive wear on the components, even despite properalignment, through the repetitive motion inherent to pumping operations.Finally, non-metallic (e.g., ceramic) components sometimes do nottolerate such hard connections as well. Hence, there is a need foranother means of translating the motion of a thrust rod (or, for thatmatter, any driving element) to a plunger.

BRIEF SUMMARY OF THE INVENTION

Various embodiments of the invention provide pumps, plungers and plungerassemblies, as well as methods of using them. In accordance with someembodiments, a plunger may comprise a ceramic material and/or may have afacial profile that may allow for more efficient pumping operations. Inparticular embodiments, for example, a plunger may have a facial profilethat allows for deformation of at least a portion of the plunger whenthe face of the plunger is in contact with a pressurized fluid. Otherembodiments provide plunger assemblies, which may comprise a flexiblecoupling attachment. Yet other embodiments provide pumps comprising suchplungers and/or plunger assemblies.

Merely by way of example, one set of embodiments provides plungers,which may comprise a metal, a ceramic material, etc. and which may befor use in pumps. In some embodiments, a plunger may be generallycylindrical in shape. In other embodiments, the plunger may have othercross-sectional shapes. In particular embodiments, the plunger may havea cross-sectional diameter of between about one-quarter inch and aboutthree inches.

One plunger in accordance with various of these embodiments may comprisea first portion which may be configured to be slidably disposed at leastpartially within a plunger housing, as well as a second portion. Thesecond portion might have a facial profile defining an opening. In someembodiments, the second portion might be configured to be exposed to apump chamber and/or in contact with a fluid, such that a reciprocalmotion of the plunger with respect to the pump chamber can exertpressure on the fluid, allowing the fluid to be pumped. In particularcases, when the plunger is in contact with the fluid, the fluid mayexert sufficient pressure on the facial profile to cause a deformationof the second portion of the plunger.

In accordance with certain embodiments, the plunger has an exteriordiameter configured to fit an interior diameter of the plunger housingto within a certain tolerance when no pressure is applied to the facialprofile. When the fluid exerts sufficient pressure on the facial profileto cause a deformation of the second portion of the plunger, thedeformation may reduces the certain tolerance. In some cases, thesufficient pressure exerted on the facial profile to cause a deformationof the second portion of the plunger may be between about 500 pounds persquare inch and about 6000 pounds per square inch. In some embodiments,operation of the plunger may result in a certain amount of leakage ofthe fluid along the length of the plunger, and/or the deformation of thesecond portion of the plunger may function to reduce the certain amountof leakage.

In some embodiments, a ratio of a cross-sectional diameter of theopening defined by the facial profile to a cross-sectional diameter ofthe plunger may be between about 0.3 and about 1.0. In otherembodiments, the facial profile may define an opening with across-section that is between about one-eighth inch and about threeinches in diameter, and/or with a length between about three-eighthsinch and about one-and-one-quarter inch. In some cases, the facialprofile defines an opening that is roughly hemispherical in shape,and/or the opening can have a diameter that is approximately equal to across-sectional diameter of the plunger. In other cases, the facialprofile might define an opening with a keyhole shape and/or a channel ina face of the plunger. The length of the channel might span across-sectional diameter of the plunger, and/or the width of the channelmight be about one-quarter to about three-quarters of a cross-sectionaldiameter of the plunger. In some cases, the plunger may be configured tobe coupled with a flexible coupling assembly.

Another set of embodiments provides plunger assemblies, which can beconfigured to be used in pumps and/or which can comprise a plunger,including without limitation the plungers described above. In accordancewith some embodiments, a plunger assembly may comprise a plunger havingan axis, a first end portion and/or a second end portion. The first endportion may be configured to be coupled with a flexible couplingassembly, and/or the second end portion may be configured to be exposedto a pump chamber. Hence, in some cases, a reciprocal motion of theplunger along the axis of the plunger can result in the pumping of afluid through the pump chamber.

The plunger assembly might further comprise a drive element having anaxis and/or a flexible coupling assembly coupled with the first endportion of the plunger and further coupled with the drive element. Thedrive element may be configured for reciprocal motion along the axis ofthe drive element, and/or the flexible coupling assembly may beconfigured to translate the reciprocal motion of the drive element tothe plunger, causing a reciprocal motion of the plunger along the axisof the plunger. In particular embodiments, the flexible couplingassembly might comprise a length of flexible tubing. In otherembodiments, the drive element might be configured to be coupled with adrive mechanism, which may be capable of providing the reciprocal motionof the drive element.

In some embodiments, the axis of the plunger and the axis of the driveelement may be generally axially aligned, and/or the flexible couplingassembly may be configured to allow the axis of the plunger and the axisof the drive element to be aligned relatively imprecisely. In otherembodiments, axis of the plunger and the axis of the drive element mightnot be axially aligned, and/or the flexible coupling assembly mayconfigured to translate the reciprocal motion of the drive element tothe plunger, causing a reciprocal motion of the plunger along the axisof the plunger, even though the respective axes of the drive element andthe plunger are not axially aligned.

Another set of embodiments provides plunger pump assemblies. Inaccordance with some embodiments, a pump assembly might comprise a pumpbody, which might define a pump chamber, perhaps with an inlet portand/or an outlet port. The pump body may further define a plunger portdisposed between the inlet port and the outlet port. The assembly caninclude a first check valve in fluid communication with the inlet portof the pump chamber and/or a second check valve in fluid communicationwith the outlet port of the pump chamber. The first check valve might beconfigured to allow a fluid to flow only into the pump chamber and/orthe second check valve might be configured to allow the fluid to flowonly out of the pump chamber.

In particular embodiments, the pump assembly can further include aplunger housing, which may define a cylindrical bore having an interiordiameter. The plunger housing can be disposed within the plunger port.In accordance with certain embodiments, the pump assembly can alsoinclude a plunger. In some cases, the plunger can be cylindrical andthus can have an exterior diameter. In particular embodiments, theceramic plunger is slidably disposed within the cylindrical bore, suchthat the plunger can be reciprocated back and forth within the bore.Thus, the fluid can be moved from the inlet port of the pump chamber tothe outlet port of the pump chamber through the reciprocal action of theplunger. The plunger may be similar to those described above and/or maycomprise an end portion with a facial profile defining an opening. Inparticular embodiments, the plunger and/or the housing may comprise aceramic material. In some cases, when the end portion of the plunger isin contact with the fluid, the fluid may exert sufficient pressure onthe facial profile to cause a deformation of the end portion of theplunger. In other cases, the plunger may be coupled with a flexiblecoupling assembly, which may be further coupled with a drive system.Hence, the drive system may impart, via the flexible coupling assembly,a reciprocating force on the plunger sufficient to reciprocate theplunger back and forth within the bore.

In a certain aspect, the exterior diameter of the ceramic plunger canfit the interior diameter of the bore to within a certain tolerance(perhaps in the range from about 1.0 microns to about 6.0 microns),and/or the deformation of the end portion of the plunger may sufficientto reduce the certain tolerance. In another aspect, a surface of theplunger may define at least one discontinuity, and/or the discontinuitymay be configured to reduce the escape of the fluid through the bore.

In accordance with various embodiments of the invention, a plungerand/or plunger housing can comprise an aluminum oxide. In otherembodiments, the plunger and/or housing can comprisetransformation-toughened zirconia. Those skilled in the art willrecognize that other materials (including without limitation other typesof ceramics) can be employed as well, however, without varying from thescope of the invention. Merely by way of example, the plunger and/or theplunger housing can comprise an alumina, comprising 99.5 percent Al₂O₃ ametal, etc.

Another set of embodiments provides fluid injection systems. Oneexemplary fluid injection system can comprise a plunger pump assembly,perhaps as discussed above, and can further comprise a drive systemconfigured to impart a generally reciprocal force on a plunger. Variousembodiments can utilize any of a variety of drive mechanisms. Merely byway of example, in some embodiments, the drive system can comprise adiaphragm motor. The diaphragm motor can be dynamically coupled with theplunger of the pump assembly and can be configured to reciprocally slidethe plunger back and forth in the bore of the plunger housing. In thisway, the diaphragm motor can operate to move a fluid from the inlet portof the pump chamber to the outlet port of the pump chamber. Someexemplary fluid injection systems can further include one or more fluidsources, some of which can be in fluid communication with the firstcheck valve of the pump assembly and/or with the diaphragm motor. Insome cases, some of the fluids can be pressurized.

In one aspect, the diaphragm motor can include a diaphragm and a linkagecoupled with the diaphragm. The linkage can also be coupled with theplunger. In such embodiments, a fluid source can be in fluidcommunication with the diaphragm. Those skilled in the art willappreciate, therefore, that the diaphragm motor can be configured toreciprocally slide the plunger back and forth in the bore in response toa fluid pressure imposed on the diaphragm by the fluid source.

Another set of embodiments provides methods of using a plunger to pumpfluids. In accordance with some embodiments, an exemplary method cancomprise providing a plunger and/or moving the plunger in a reciprocalmotion along an axis of the plunger. The plunger may be similar to thosediscussed above and/or may comprise a first portion configured to beslidably disposed at least partially within a plunger housing. Theplunger may further comprise a second portion having a facial profiledefining an opening. In some cases, the second portion may be configuredto be exposed to a pump chamber and/or in contact with a fluid, suchthat a reciprocal motion of the plunger with respect to the pump chambercan exert pressure on the fluid, allowing the fluid to be pumped. Whenthe plunger is in contact with the fluid, the fluid may exert sufficientpressure on the facial profile to cause a deformation of the secondportion of the plunger.

In some cases, moving the plunger may result in a certain amount ofleakage of the fluid along the length of the plunger, and/or thedeformation of the second portion of the plunger may function to reducethe certain amount of leakage. In other cases, the plunger may have anexterior diameter configured to fit an interior diameter of the plungerhousing to within a certain tolerance when no pressure is applied to thefacial profile. When the fluid exerts sufficient pressure on the facialprofile to cause a deformation of the second portion of the plunger, thedeformation might reduces the certain tolerance.

In accordance with other embodiments, a method might comprise providinga plunger, which could have an axis, a first end portion and/or a secondend portion. The first end portion might be configured to be coupledwith a drive element, and/or the second end portion might be configuredto be exposed to a pump chamber. Hence, a reciprocal motion of theplunger along the axis of the plunger may result in the pumping of afluid through the pump chamber. In some embodiments, the method furthercomprises providing a drive element having an axis; the drive elementmay be configured for reciprocal motion along the axis of the driveelement. In further embodiments, the drive element might be coupled withthe first end portion of the plunger, perhaps using a flexible couplingassembly. The flexible coupling assembly might be configured totranslate a reciprocal motion of the drive element to the plunger,causing a reciprocal motion of the plunger along the axis of theplunger, and/or the method might include imparting a reciprocal motionto the axis of the drive element, thereby causing the plunger to move ina reciprocal motion along the axis of the plunger.

In particular embodiments, the plunger can be configured to be slidablydisposed at least partially within a plunger housing, and/or the secondend portion might have a facial profile defining an opening and/or mightbe configured to be exposed to a pump chamber and in contact with afluid. In such embodiments, the method can further comprise exertingsufficient pressure on the second end portion of the plunger to cause adeformation of at least part of the plunger. The plunger might have anexterior diameter configured to fit an interior diameter of the plungerhousing to within a certain tolerance when no pressure is applied to thefacial profile, and/or when sufficient pressure is exerted on the facialprofile to cause a deformation of the at least part of the plunger, thedeformation might reduce the certain tolerance. Further, operation ofthe plunger might result in a certain amount of leakage of the fluidalong the length of the plunger, and/or the deformation of the secondportion of the plunger might functions to reduce the certain amount ofleakage.

The invention has been briefly summarized above. A further understandingof specific details and features of the invention may be realized byreference to the remaining portions of the specification and thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing illustrating a fluid injection system inaccordance with various embodiments of the invention.

FIG. 2 is a sectional drawing of an injector head, including a pumpassembly in accordance with various embodiments of the invention.

FIG. 3A is a perspective drawing of a plunger housing and plunger thatcan be used in accordance with various embodiments of the invention.

FIG. 3B is a perspective drawing of the plunger of FIG. 3A slidablydisposed within the plunger housing.

FIGS. 4A and 4B are graphs illustrating, for a variety of fluids, thesealing performance of pump assemblies in accordance with variousembodiments of the invention.

FIG. 5 is a schematic drawing illustrating a fluid injection and pumpassembly in accordance with various embodiments of the invention.

FIG. 6 is a process flow diagram illustrating a method that can be usedto produce a pump assembly in accordance with various embodiments of theinvention.

FIGS. 7A-7C illustrate plungers with surface discontinuities along theirlengths, in accordance with various embodiments of the invention.

FIGS. 8A-8J illustrate plungers having a variety of facial profiles, inaccordance with various embodiments of the invention.

FIG. 9 is a graph illustrating the relative sealing performances ofpumps having plungers with a variety of facial profiles, in accordancewith various embodiments of the invention.

FIG. 10A is an illustration of a plunger and a thrust rod adapter inaccordance with various embodiments of the invention.

FIG. 10B is an illustration of a plunger assembly in accordance withvarious embodiments of the invention.

FIG. 10C is another illustration of a plunger assembly in accordancewith various embodiments of the invention.

FIG. 11 is a process diagram illustrating a method of producing and/orimplementing plungers and/or pumps in accordance with variousembodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Among other things, embodiments of the invention provide plunger pumps,as well as methods for their production. In accordance with certainembodiments, a plunger pump can comprise a pump chamber and a ceramicplunger housing, as well as a ceramic plunger slidably disposed within abore defined by the plunger housing. In a certain aspect, the outsidediameter of the plunger can fit the inside diameter of the housing towithin a certain tolerance, and the tolerance can operate to preventand/or minimize the material being pumped from escaping from the pumpchamber through the bore. In another aspect, for a plunger and housingexhibiting a certain tolerance, the length of the housing can bedesigned to control the rate of any leakage.

According to various embodiments of the invention, a ceramic plunger andhousing can operate to allow an essentially leak-proof pumping mechanismwithout the need for any packing materials, which, those skilled in theart will recognize, can tend to degrade over time, requiring periodicmaintenance and/or replacement. Thus, the ceramic housing and/or plungercan provide improved pumping performance over a longer period of timeand with less maintenance than traditional plunger/packing arrangements.For instance, pumps according to certain embodiments often consume fewerexpendable parts (e.g., packing, packing nuts, etc.) and require lessadjustment and/or maintenance (and therefore less travel time forpersonnel).

In some cases, the plunger and/or housing can be lubricatedperiodically, and in other cases, the components can be“pre-lubricated,” such that periodic addition of lubricants to thecomponents in unnecessary. In still other cases, the material beingpumped can itself act as a lubricant. In further cases, the ceramicplunger and/or housing can be operated without any lubricant at all,since the ceramic materials of which the housing and/or plunger arecomprised can be relatively impervious to frictional degradation, andsince the tolerance between the plunger and housing reduces thecontinual frictional contact between the two components. Thus, byreducing frictional contact, both power requirements and component wearcan be reduced. Further, ceramic components in accordance withembodiments of the invention can be relatively impervious totemperature, wear, corrosion and reactive chemicals when compared tomore traditional materials, such as steel and the like. Hence, pumps inaccordance with embodiments of the invention can pump a variety ofmaterials at various pressures and temperatures while exhibitingrelatively low power requirements, wear and/or leakage.

Turning now to FIG. 1, an injection system 100 is illustrated inaccordance with certain embodiments of the invention. Injection system100 generally includes an injection head 104 and a drive system 108. Thedrive system 108 can be any of several drive systems known in the art,including electric motors, lever-operated drives, and the like. In theillustrated embodiment, the drive system 108 comprises a diaphragmmotor, which can be used to provide reciprocating action for a plungerin accordance with certain embodiments of the invention, an externalhousing 112 and a diaphragm cover 116, which can be fixedly attached tohousing 112 (e.g., via hex bolts 120 a, 120 b). Although illustrated inFIG. 1 as a cutaway drawing, those skilled in the art will recognizethat diaphragm cover 116 and the portion of housing 112 to which it iscoupled can form two generally circular, opposing faces.

The diaphragm motor can comprise a molded diaphragm 124 adjacent to arigid diaphragm plate 128. The diaphragm plate 128 can be fastened tothe diaphragm 124, as well as to a linkage 132, perhaps using a hexbolt, to allow movement of the diaphragm 124 (and, therefore, thediaphragm plate 128 as well) to impose generally oscillating lateralforces on the linkage 132, causing it to move reciprocally. The linkage132 can be fastened to a thrusting rod 136 via a rod adapter 140, andthe thrusting rod can include a coupling mechanism 144, that can becoupled with a plunger 148. The plunger 148 can be disposed generally ina pump assembly (e.g., injection head 104), in a manner described inmore detail below. The coupling mechanism 144 can, in certainembodiments, comprise a pin. In certain embodiments, as described inmore detail below, the coupling mechanism 144 can comprise a couplingassembly, which may be flexible. Also fixedly coupled with the diaphragmplate 128 can be a return spring 152, the function of which is describedin detail below.

In some embodiments, the circumference of diaphragm 124 can besandwiched between diaphragm cover 116 and housing 112 (and, optionally,secured by hex bolts 120 a, 120 b), forming two chambers 156, 160, witha generally airtight seal therebetween. Those skilled in the art willappreciate, therefore, that the diaphragm 124 can be made of anyflexible, moldable material that can be used to form an airtight seal,including, for example, silicone, rubber, nylon or the like, using anyof a variety of well-known fabrication methods. The diaphragm plate 128can comprise any rigid material capable of withstanding the sometimesopposing forces imparted by the diaphragm 124 and the return spring 152.For instance, in certain embodiments, the diaphragm plate 128 can bemade of steel, aluminum or the like. Those skilled in the art willappreciate that the return spring 152 can comprise any material ofsufficient strength that is capable of remaining elastic underrepetitive compressive loads, such as, merely by way of example, acadmium-plated carbon steel.

The linkage 132 can be coupled with a reciprocating mechanism 164 by astirrup assembly 168, which can be attached to the reciprocatingmechanism 164 with a pin and can define a collar around the linkage 132,secured, for example, by a set screw. The use of such a stirrup assemblyis known to those skilled in the art and therefore will not be describedin further detail. In this way, any lateral movement of the linkage 132can be translated to a toggling force on the reciprocating mechanism164.

In general, reciprocating mechanism 164 can be any mechanism and/ordevice that operates to translate a constant fluid pressure into agenerally oscillating force, and, in some embodiments, can operate by atoggling mechanism. Merely by way of example, reciprocating mechanism164 can comprise a “flipper” spring valve known to those skilled in theart. Reciprocating mechanism 164 can be coupled with a fluid source viaan adapter (not shown on FIG. 1), such as a ¼″ threaded femalereceptacle known to those skilled in the art. In this way, thereciprocating mechanism 164 can receive a pressurized fluid. Thereciprocating mechanism also can be coupled with both an exhaust vent170, as well as to a pilot line 172, which can provide fluidcommunication from reciprocating mechanism 164 to the chamber 156. Inthis way, reciprocating mechanism 164 can provide switchable fluidcommunication between the pressurized fluid source, the chamber 156 andthe exhaust vent 170.

Embodiments of the invention can be configured to operate with a varietyof pressurized fluids. (It should be noted as well that other means canbe used, including lever action, electrical and/or gas motors, etc.)Often such fluids can be gases, such as pressurized air, natural gas,wellhead gases, and the like, but they can, in accordance with someembodiments, be liquids as well. In some embodiments, the fluid can bepressurized to any suitable pressure, which, in some embodiments can beabout 15-150 psi, and/or a regulator can be used to reduce the operatingpressure of the gas. Merely by way of example, fluid injection systemsin accordance with various embodiments can be used to inject an additiveinto a pressurized fluid stream, such as a gas line or the like. In suchembodiments, a pilot line branching off of the main gas line can be thesource of pressurized fluid to drive the diaphragm motor.

In a default state, return spring 152 is under no compression, diaphragmplate 128 is disposed proximate to diaphragm cover 116, and thereciprocating mechanism 164 is configured (as a result of the positionof the linkage 132) to route the pressurized fluid toward the chamber156. In operation, when a pressurized fluid source is attached to thereciprocating mechanism 164, the fluid flows from the reciprocatingmechanism 164, through the pilot tube 172 and the adapter 176, into thechamber 156. The fluid can create sufficient pressure in the chamber 156to displace the diaphragm 124 away from the diaphragm cover 116, therebyplacing the return spring 140 under compression. This displacement willalso cause the linkage 132 to move generally away from the direction ofthe diaphragm cover 116 and toward the injection head 104.

At a certain point, (i.e., when the diaphragm 124 has moved sufficientlyfar away from to the diaphragm cover 116), the linkage 132 will havecompleted a full forward stroke, displacing trip stirrup 168, thrustingrod 136, and, by extension, plunger 148. At this point, the displacementof trip stirrup 168 will toggle the reciprocating mechanism 164. Whentoggled, the three-way valve of the reciprocating mechanism 164 willoperate to close the connection between the pressurized fluid source andthe chamber 156 and will instead allow the pressurized fluid already inchamber 156 to vent to the environment (and/or a suitable collectiondevice) through exhaust vent 170, thereby acting to reduce the pressurein the chamber 156. The other chamber 160 can be vented to theatmosphere, for instance, through vent 180, to maintain roughlyatmospheric pressure in that chamber 160, preventing any positive ornegative pressure therein from affecting the movement of the diaphragm124.

When the pressure in the chamber 156 has decreased sufficiently, theforce imposed on the diaphragm plate 128 by that pressure will beovercome by the force of the loaded return spring 152, causing the plate128 (and, in connection, the diaphragm 124) to return to the defaultposition, forcing the linkage 132 to reciprocate toward the diaphragmcover 116 and away from the injection head 104, thereby displacing tripstirrup 168 toward its default position and moving the thrusting rod 136and plunger 148 in the direction of the injection head 104.(Alternatively, instead of using a return spring 152, the diaphragmmotor can be configured so that pressurized fluid can be routedalternately to chambers 156 and 160, thereby producing a similarreciprocal effect on the diaphragm 124.) When the linkage 132 hasreciprocated to the extent of its back stroke, the displacement of thetrip stirrup 168 will again toggle the reciprocating mechanism 164,causing the process to repeat. In this way, the diaphragm motor, asdescribed generally above, can produce a reciprocating action of thelinkage 132 when exposed to a constant pressure fluid source. Via thethrust rod 136, the reciprocating action of the linkage 132 can causethe plunger 148 to move reciprocally within the injector head 104.

As discussed in detail below, the plunger 148 contacts the fluid to beinjected, which can be a different fluid than the pressurized fluid usedto drive the diaphragm motor, discussed above. Merely by way of example,materials that can be injected using embodiments of the inventioninclude surfactants, defoamers, biocides (including bleach), corrosioninhibitors (including toluene, xylene, etc.), demulcifiers, solvents,paraffin inhibitors, scale inhibitors, pH buffers, hydrogen sulfidescavengers, water clarifiers, coagulants, methanol, acids (including, inparticular, hydrochloric, phosphoric and acetic acids), alcohols(including, in particular, methanol), and the like. Hence, a widevariety of materials can be pumped/injected by embodiments of theinvention, and, in some cases, a small amount of the material to beinjected might escape the injector head 104 via transmission along theplunger 148. To accommodate such situations, and/or to allow themonitoring of any leakage (e.g., for maintenance purposes), the housing112 can define a drain 184 to collect and/or allow the escape ofleakage.

Turning now to FIG. 2, an injection head 104 in accordance with variousembodiments of the invention is illustrated. The injection head 104 cangenerally comprise a pump assembly, including a pump body 200. Theinjection head 104 can be attached to a drive mechanism, such as thedrive system 108 of FIG. 1, to form an injection system such as thatrepresented by reference numeral 100.

The pump body 200 can define a pump chamber 204, which can have an inletport 208 and an outlet port 212. The inlet port 208 can be in fluidcommunication with a check valve 216, known to those skilled in the art,and pump body 200 can include an attachment mechanism 200, which may bea threaded bushing, etc., for attaching a supply line to be in fluidcommunication with the inlet port 208 through the check valve 216. Thus,when in operation, as discussed below, the injection head 104 can drawfluid from the supply line, and the check valve 216 can prevent thebackflow of any fluid from the pump chamber 204 into the supply line.Likewise, the outlet port 212 can be in fluid communication with a checkvalve 224, and further in fluid communication with a discharge line,through attachment means 228. Either check valve 216, 224 can be asuction ball assembly, which, as those skilled in the art willrecognize, will effectively allow for one-way transmission of fluid. Ifnecessary, check valve 224 can include a spring to provide increasedresistance and further ensure against backflow into the pump chamber204. Optionally, injection head 104 can include a threaded priming key236, which, when backed out of the priming port 240, will create a smallvacuum in the pump chamber 204, drawing fluid through the inlet port 208and thereby priming the injection head 104 for pumping.

The pump body 200 can further define a plunger port 244, which, incertain embodiments, extends from the exterior of the pump body 200 tothe pump chamber 204. As illustrated in FIG. 2, the plunger port 244 candefine a relatively narrow void extending away from the pump chamber 204and can define a wider void near the exterior of the pump body 200. Theplunger port 244 can be adapted to hold a plunger housing 248 within thewider void. Generally, the plunger housing 248 can fit relativelytightly within the plunger port 244 in order to prevent excess leakageof fluid from the pump chamber 204. As discussed in greater detailbelow, the relative sizing of the plunger housing 248 and the interiorof the plunger port 244 can, in some cases, be designed to place theplunger housing under compression. In certain embodiments, a cap 252 canbe used to secure the plunger housing 248 within the plunger port 244.In other embodiments, the cap can serve additional purposes. Forinstance, the cap 252 could be designed to attach to the pump body 200with a compression fitting, such that attachment of the cap 252 could beused to place the plunger housing 248 under compression. In still otherembodiments, the cap 252 can comprise a fitting for attaching the pumpinsertion head 104 to a drive mechanism, such as the diaphragm motor ofFIG. 1.

A plunger 148 can be slidably disposed within the plunger housing 248,such that, when fully inserted, the plunger 148 extends through the pumpchamber 204 (e.g., proximate to the far wall of the pump chamber 204),effectively displacing a substantial proportion of the volume of thepump chamber 204. The plunger 244 can, thereafter, be withdrawn from thepump chamber 204, effectively removing the displacement and therebycreating a state of relative vacuum in the pump chamber 204 and drawingfluid from the inlet port 208. When reinserted in the pump chamber 204,the plunger 148 can again displace a substantial proportion of thevolume of the chamber 204, forcing at least a portion of the fluid inthe pump chamber 204 through the outlet port 212 (the check valve 216can prevent discharge through the inlet port 208. In this fashion, ifmoved in and out of the pump chamber 204 with a reciprocating action,plunger 148 can be used to pump fluid from the inlet port 208 throughthe pump chamber 204, to the outlet port 212. Thus, when coupled with adrive system motor, such as that illustrated in FIG. 1, the injectorhead 104, through the action of the plunger 148, can be used to pump afluid from a supply line to a discharge line, and can further be used toinject a first fluid into a second fluid. In some cases, the secondfluid can be the pressurized fluid that powers the diaphragm motor,allowing for an essentially self-powered injection system.

In accordance with certain embodiments, the plunger 148 and/or plungerhousing 248 can comprise a ceramic material. In many cases, the plunger148 and housing 248 will comprise like materials, although in othercases, the plunger 148 and the housing may comprise different materials.Merely by way of example, in a particular embodiment, plunger 148 and/orplunger housing 248 can comprise an alumina ceramic. There are a varietyof such compounds commercially available, including, for instance, aceramic blend commonly known in the art as AD-995, which, those skilledin the art will appreciate, generally comprises about 99.5 percentAl₂O₃. AD-995 is commercially available from Coorstek, Inc., of Golden,Colo. Those skilled in the art will further recognize that other aluminacompounds can be used as well. For example, certain embodiments of theinvention employ a plunger 148 and/or housing 248 made of a ceramiccomprising approximately 99.8 percent Al₂O₃, known in the art as AD-998,and/or an alumina comprising approximately 98.5 percent Al₂O₃, known inthe art as FG-995, all available from Coorstek.

In still further embodiments, other ceramics can be used as well,including, for example, those comprising aluminum oxide. Some suchceramics further comprise proportions of zirconia, and one exemplaryembodiment employs a material known in the art as transformationtoughened zirconia (“TTZ”), also commercially available from Coorstek.Those skilled in the art will recognize that TTZ can, in some cases, bepartially stabilized, for instance, by the introduction of certainproportions of MgO. Various embodiments can comprise other types ofzirconia and/or alumina compounds, such as those known in the art astetragonal zirconia polycrystals (“TZP”), yttria stabilized zirconiapolycrystals (“YTZP”), ceria stabilized tetragonal zirconia polycrystals(“CeTZP”), other ceria compounds, and/or zirconia toughened aluminas(“ZTA”). Those skilled in the art will recognize, based on thedisclosure herein, that other ceramic materials may be used as well,including for instance, silicon carbides and tungsten carbides. Incertain aspects, such materials often will have a relatively lowco-efficient of thermal expansion and/or a relatively high degree ofabrasion resistance. In some cases, the plunger and/or the plungerhousing can be coated in order to improve performance parameters such aswear resistance, coefficient of friction, etc. Virtually any desiredmaterial can be used as a coating, although monolithic materials areused most often. In particular cases, any of the materials discussedabove can be used as a coating material, depending on the requirementsof specific implementation. In yet other embodiments, the plunger and/orplunger housing may comprise a metal, such as aluminum, steel, and/orany of several alloys.

Turning briefly now to FIG. 3A, a perspective drawing of the plunger 148and the plunger housing 248 is illustrated. As illustrated, the plungerhousing 248 can describe a bore, which, in some embodiments, can begenerally circular, having an interior diameter D₁. The plunger 148, onthe other hand, can have an exterior diameter D₂. In accordance withsome embodiments the diameter D₂ of a plunger may be between aboutone-quarter inch and about three inches. In other embodiments, thediameter D₂ may be between about three-eighths inch and two inches, andin still other embodiments, the diameter D₂ may be between aboutone-half inch and one and one-half inches. Of course, embodiments of theinvention are not limited to any particular sized plungers.

Generally, the exterior diameter D₂ of the plunger 148 will be smallerthan the interior diameter D₁ of the bore, such that the plunger 148 canbe slidably disposed within the plunger housing 248, as illustrated, forexample, in FIG. 3B. In accordance with some embodiments of theinvention, the plunger 148 and/or plunger housing 248 can bemanufactured so that the tolerance (i.e., clearance) between D₁ and D₂is within a few microns. For example, in certain embodiments, thetolerance between D₁ and D₂ can be in the range of about 1.2 microns toabout 1.8 microns. In other embodiments, the tolerance between D₁ and D₂can be in the range of about 1.47 microns and about 2.45 microns. Insome embodiments, as discussed above, the plunger 148 and/or housing 248can be manufactured of ceramic materials, which, those skilled in theart will recognize, can have a relatively low coefficient of thermalexpansion, allowing for relatively precise tolerances even inapplications where the plunger 148 and/or housing 248 might be subjectedto variations in temperature.

In some embodiments, as discussed below, in addition to the tolerancebetween D₁ and D₂, the length L of the housing 248 can impact theability of the housing to prevent leakage of the material being pumped.Generally, the longer the plunger housing 248, the lower the rate ofleakage that would be expected for a plunger and housing having a giventolerance. Thus, for pumps operating with materials with lower Reynoldsnumbers and/or pumps operating at higher pressures, either a tightertolerance between the plunger and the housing and/or a longer housingcan be employed to further assure against unacceptable leakage rates. Insome exemplary embodiments, the plunger housing can be between 0.5 and10.0 cm, although longer and/or shorter housings can be used, dependingon operating conditions, as discussed herein. Moreover, as discussed indetail below, the characteristics of the facial profile and/or outersurface of the plunger 148, as well as the inner surface of the plungerhousing 248, can be modified to effect different leakage rates ofdifferent materials.

Returning now to FIG. 2, the tolerance between the exterior diameter ofthe plunger 148 and the housing 248 can allow the plunger 148 and theplunger housing 248 to be used in the operation of the injection head104 without the need for any seals, gaskets or lubricants. In effect,the relatively precise tolerance between the two parts can allow theplunger 148 to reciprocate freely within the plunger housing 248, in themanner described above, while preventing any substantial leakage offluid through the bore of the plunger housing 248. (Of course, any fluidthat does leak through the bore can be collected and/or evacuatedthrough drain 180, as described above with regard to FIG. 1). Thoseskilled in the art will recognize that the amount of leakage through thebore depends on the properties of the fluid in pump chamber 204,including the pressure imposed on the fluid and the Reynolds number ofthe fluid, as well as the length of the plunger housing 248 and thetolerance between the exterior diameter of the plunger 148 and theinterior diameter of the housing 248.

FIGS. 4A and 4B depict charts (400 and 404, respectively) illustrating aset of calculated leakage rates (also known in the art as “blow by”rates) for particular embodiments of the invention, with respect toseveral exemplary fluids. FIG. 4A illustrates the calculated rates atwhich four different fluids could be expected to blow through the boreof an exemplary plunger housing during operation of the injector head.The exemplary plunger housing used to calculate the rates is 1.158inches in length and can accommodate a 0.375 inch plunger with 1.27microns of clearance on either side (for a total of 2.54 micronstolerance). The calculated values exhibited in FIG. 4A assume that theplunger has a face that is flat and perpendicular to the length of theplunger and that the plunger includes no discontinuities along itslength. For relatively low-viscosity fluids, such as Methanol, underrelatively high pressure, somewhat greater leakage rates might beexpected (slightly more than 0.7 cm³ per minute at a pressure of 6000psi). On the other hand, with more viscous fluids (for example, withethylene glycol), even at such high pressures, very little leakage wouldbe expected. Given the disclosure herein, those skilled in the art willrecognize that increasing the length of the housing and/or decreasingthe tolerance between the plunger and the housing can reduce theexpected leakage rates.

For instance, FIG. 4B includes a chart 404 depicting calculated data foran exemplary plunger housing similar to the plunger housing analyzed inFIG. 4A, except that the tolerance between the plunger and the housingis 0.127 microns (total). As illustrated by the chart 404, the leakagerates for this embodiment are almost an order of magnitude lower thanthose for the exemplary plunger of FIG. 4A. In this way, those skilledin the art will appreciate, reducing the clearance between the plungerhousing bore and the plunger can provide significant improvements inleakage performance. Those skilled in the art will recognize, as well,that a longer plunger housing likewise will lead to reduced leakage. Inaddition, as discussed below, altering the facial profile of the plungerand/or introducing discontinuities in the surface along the length ofthe plunger can affect expected leakage rates as well.

Turning now to FIG. 5, an alternative embodiment of a pump 500 inaccordance with the present invention is illustrated. The pump 500generally comprises a power head 504 and a pump body 508. The power headcan include any drive system (not shown). A piston-plunger assembly 516is disposed within the power head 504, with the plunger portion 520 ofthe assembly 516 extending into the pump body 508. The drive system canbe any device that is capable moving the piston-plunger 516 verticallyin a generally reciprocal fashion (including without limitation thedrive systems described elsewhere in this disclosure), and it can beintegrated with the power head 504, or alternatively, can be a separatedevice that can be attached via suitable fastening apparatus. The powerhead 504 can be securely and/or removably attached to the pump body 508,using fasteners such as bolts, locknuts and the like. In certainembodiments, the power head 504 can be coupled with the pump body via athreaded attachment member 522. Optionally, a stroke-limiter 524 can beimplemented in the power head 504, to limit the length of the stroke ofthe piston-plunger 516 and thereby control the pump rate, pump chamberpressure, etc.

The reciprocating mechanism 512 can be coupled with the piston plunger516 in any of several different ways. For instance, in certainembodiments, the reciprocating mechanism 512 can be an electric motorwith a linkage, and the linkage can be coupled with the piston plunger516. Methods of coupling an electric motor to a piston to produce agenerally reciprocal motion are well known in the art and will not bediscussed in detail herein. In other embodiments, the reciprocatingmechanism 512 can comprise a device similar to the toggling switchdiscussed in conjunction with FIG. 1, and can be in fluid communicationwith a pressurized fluid source. In such embodiments, the reciprocatingdevice 512 can be operable to pressurize/depressurize, in oscillatingfashion, a chamber 528 within the power head 504, forcing the pistonplunger 516 downward against a return spring 532, which, when thepressure in the chamber 520 is reduced, can force the piston-plunger 516up to its original position.

Other means of imparting reciprocal motion to the piston-plunger 516(including manual manipulation of the piston-plunger 516, in which case,the reciprocating mechanism 512 could be a lever coupled with thepiston-plunger 516) can be incorporated within the scope of theinvention as well. Those skilled in the art will recognize that certainillustrated components, such as, for example, return spring 532, may beconsidered optional, and other components well known in the art can beincluded, depending on the nature of the reciprocating mechanism 512, solong as the chosen device operates move piston-plunger 516 in avertical, generally reciprocal fashion.

The pump body 508 can define a pump chamber 536 having an inlet port 540and an outlet port 544, as well as an optional bleeder valve 548. Theinlet port 540 and the outlet port 544 each can have a check valve (552and 556, respectively), and the inlet port 540 can be in fluidcommunication (perhaps through the check valve 552) with an adapter 560for attachment to a line supplying the material to be pumped. Likewise,outlet port 544 can be in fluid communication (e.g., through the checkvalve 556) with an adapter 564 for a discharge line. The discharge lineoptionally can be configured to feed into a pressurized line, so thatpump 500 can be used to inject additives, etc. into pressurized fluidstreams. As discussed above, in certain embodiments, the pressurizedfluid stream can be used to power the reciprocating device 512, suchthat pump 500 can use the pressure of a fluid stream itself to introduceadditives into that stream.

In the illustrated embodiment, the pumping operation is similar to thatdescribed above. The plunger portion 520 can be drawn out of the pumpchamber 536 by the action of the reciprocating device 512, creatingnegative pressure in the pump chamber 536. The negative pressure willdraw fluid through the inlet adapter 560, check valve 552 and inlet port540, into the pump chamber 536. When the piston-plunger has reached theend of its upward stroke (e.g., when it strikes stroke limiter 524), itwill begin a downward stroke. Prevented by the check valve 552 fromescaping the pump chamber 536 through the supply line, the material inthe pump chamber will be evacuated through the port 554, check valve 556and adapter 564, perhaps to an attached discharge line.

To stabilize the plunger 520 and/or prevent migration of pumped materialout of the pump chamber 536 and along the axis of the plunger 520, aplunger housing 572 can be employed. The plunger housing 572 can besituated within a plunger port 576 defined by the pump body 508, and thehousing 572 can define a bore (which, in some cases, can have agenerally circular cross section and therefore can be generallycylindrical in shape), similar in some ways to the housing discussedabove with respect to FIGS. 3A and 3B. In accordance with certainembodiments, the plunger portion 520 (and/or the entire piston-plunger516), as well as the plunger housing 572, can be constructed from aceramic material, including without limitation the materials discussedin detail above. The plunger 520 can be designed to be slidably disposedwithin the plunger housing, to within a clearance (i.e., tolerance),perhaps of a few microns. In certain embodiments, the clearance can bewithin about 0.6 microns per side (1.2 microns total) to about 1.5microns per side (3.0 microns total). In this way, the plunger housing572 can provide sealing capabilities to prevent leakage of anysignificant amount of pumped material without the need for anyadditional packing material, reducing the cost and complexity ofmaintenance. Moreover, certain embodiments eliminate the need for anysort of lubricating agents, often used in the past to reduce frictionbetween the plunger and any associated packing materials, although incertain embodiments, lubricating agents (perhaps including the fluidbeing pumped) still can be used if desired.

In some embodiments, the plunger housing 572 optionally can be placedunder compression by the plunger port 580. This compression can beachieved, in some cases, by heating the plunger port 580 prior toinserting the plunger housing 572 into the plunger port 580. Otherembodiments secure the plunger housing other means, for instance throughuse of an adhesive, press fitting, capping and/or the like. Forinstance, in an embodiment where the pump body 508 is attached to thepower head 504 using a threaded attachment method (e.g., 522), theplunger port 580 can be integrated into the threaded portion of the pumpbody 508, and attaching the pump body 508 to the threaded attachment 522can operate to place the plunger port 580, and by extension, the plungerhousing 572, under compression. Regardless of the method of compressingthe plunger housing 572, however, those skilled in the art willrecognize that the compression of housing 572 can, in some cases,operate to reduce the clearance between the housing 572 and the plunger520. In such cases, the housing 572 and/or plunger 520 can be designedto accommodate changes to the interior diameter of the plunger housinganticipated as a result of the compression of the housing 572.

As discussed above, the length of the plunger housing 572 can affect thesealing performance of the housing, and various embodiments of theinvention therefore can employ plunger housings of varying lengths,depending on anticipated pressures within the pump chamber 536. Inparticular embodiments, the design of the plunger housing 572 (e.g., thehousing's length, the clearance between the housing and the plunger,etc.) can take into account the type of material to be pumped.

As alluded to above, in certain cases it can be helpful to have as closea fit as possible between a plunger port and a plunger housing, andceramic materials can be used to obtain a precise fit. In accordancewith certain embodiments of the invention, therefore, a method isprovided for producing a ceramic plunger pump assembly. In someembodiments, methods for producing plunger pump assemblies can be usedto create new pumps and/or injector heads, and, in particular, can beused to produce injector heads for any of the variety of“Texsteam™”-style pumps known in the art. In other embodiments, similarmethods can be used to retrofit existing injector heads, pump bodies,etc. in order to accommodate ceramic plungers and/or plunger housings inaccordance with various embodiments. For instance, the FloMore™ Series5200 injector head, commercially available from Richart DistributorsInc. of Oklahoma City, Okla., could be retrofit in accordance with someembodiments of the invention. Similarly, the Series 5100 air or gasdriven injectors from Texsteam Corporation™ of Houston, Tex. can beretrofit in accordance with other embodiments of the invention, and theModel 40/60/80 D-Series of pumps commercially available from SidewinderPumps, Inc.™ of Lafayette, La., can be retrofit according to certainembodiments of the invention.

FIG. 6 illustrates an exemplary method 600 for producing a ceramicplunger pump assembly in accordance with embodiments of the invention.According to method 600, a pump body is provided at block 604. The bodycan be, merely by way of example, the pump body 200 of FIG. 2. At block608, the pump body optionally can be heated from an ambient temperatureto a temperature sufficient to cause expansion of the pump body, and, inparticular, expansion of the plunger port. Those skilled in the art willrecognize that the temperature to which the pump body ideally should beheated can vary according to the material from which the pump body isconstructed. In a particular embodiment, a temperature in the range ofabout 200° F. to about 700° F., can cause sufficient expansion of theplunger port. In other embodiments a temperature in the range of about300° F. to about 500° F. might be more suitable. In still otherembodiments, a different temperature and/or range of temperatures mayproduce the best results. Those skilled in the art will recognize that,if desired, only that portion of pump body 200 that defines plunger port244 need be heated.

Those skilled in the art also will recognize that heating the pump bodycan be accomplished by a variety of methods. For instance, a portableacetylene torch can be used to heat the portion of the pump body localto the plunger port. In other embodiments, the entire pump body might beheated in an oven. In still other embodiments, an exothermic chemicalreaction could be used to apply heat to a specific portion of the pumpbody, and/or an induction coil might be used to heat a specific portionof the body. Any suitable method of heating the pump body can beemployed without varying from the scope of the invention.

At block 612, a plunger housing (e.g., 248) can be inserted into theplunger port of the pump body. In accordance with some embodiments, theinsertion procedure can be as simple as sliding the plunger housing intothe plunger port. In other embodiments, the plunger housing and/or theplunger port can be threaded and/or otherwise adapted to be matedtogether, and insertion can comprise threading the housing into theport, etc. In a particular embodiment, the plunger port might employ aridge or other positive fastening mechanism, and inserting the plungerhousing can involve ensuring that the positive fastening mechanism hasbeen engaged (i.e., inserting the plunger housing until it “clicks” intoproper position).

Optionally, in accordance with certain embodiments, the pump body can beallowed to cool (block 616). If, for example, the pump body had beenheated above the ambient temperature before the plunger housing wasinserted, allowing the pump body to cool after insertion can cause thepump body to contract, producing a tighter seal between the plunger portand the plunger housing than might otherwise be obtained. In some cases,depending on the relative sizes of the plunger port and the plungerhousing, cooling the pump body can effectively place the plunger housingunder compression (block 620). Placing the plunger housing undercompression not only can improve the seal between the plunger port andthe plunger housing, but it also can greatly improve the burst strengthof the of plunger housing, allowing it to withstand, for example,greater fluid pressures in the pump chamber. In effect, the tensilestrength of the (often metallic) pump body and the compressive strengthof the plunger housing can compliment one another, allowing for improvedoverall durability of the pump.

As discussed above, in accordance with certain embodiments, compressingthe plunger housing can, in fact, reduce the size of the bore defined bythe plunger housing, thereby reducing the clearance between the plungerhousing and a plunger slidably disposed within the plunger housing.Hence, the manufacturing process of the plunger and/or plunger housingcan account for this compression, and/or the design the plunger and/orplunger housing can be altered to incorporate marginally more clearancethan otherwise would be desired.

At block 624, a plunger can be slidably disposed within the plungerhousing in a fashion such that it can be moved into a pump chamber toperform the functions outlined above. Optionally, a capping device (suchas the cap 252, illustrated on FIG. 2) can be attached to the plungerport to secure the plunger housing within the plunger port and/or toprovide a means of attachment of the pump assembly to, for instance, adiaphragm motor. At block 632, the injector head can be attached to apowering device, for example, the drive system 108 of FIG. 1, which canbe used to reciprocate the plunger and effectuate the pumping actiondescribed above.

In accordance with some embodiments of the invention, a plunger can bemanufactured to have one or more discontinuities along the outer surfaceof the length of the plunger. These discontinuities can be filled with apacking material (e.g., a viscous fluid such as oil) before and/orduring operation of the pump in order to provide a further seal againstleakage of the material being pumped. For instance, in some cases,(e.g., where a relatively viscous material is being pumped), thediscontinuities might be left empty prior to operation of the pump, andany pumped material leaking along the length of the plunger can fill thediscontinuities, thereby effectively providing a seal again furtherleakage along the length of the plunger.

In other cases (e.g., where the pumped material has a relatively lowviscosity), the discontinuities can be filled with a relatively moreviscous packing fluid and/or lubricant prior to operation of the pump.This packing fluid/lubricant effectively can serve as a seal to blockleakage of the pumped material along the length of the plunger. Ineither case, the material filling a discontinuity in the surface of theplunger can occupy the discontinuity as well, perhaps, as the clearance(i.e., the tolerance) between the plunger and the housing. In accordancewith some embodiments of the invention, therefore, the discontinuitiescan be disposed on a portion of the plunger that remains within thehousing during the entire stroke of the plunger, such that any materialdisposed within the discontinuities can maintain contact with thehousing, whether the plunger is extended into the pump chamber orwithdrawn from the pump chamber. In alternative embodiments, the housingitself might comprises similar discontinuities on the surface of thebore, and the plunger itself might have no discontinuities.

As mentioned above, the discontinuities are optional; in manyembodiments, the plunger has no discontinuities. Moreover, the number ofand nature of the discontinuities is discretionary and can vary byapplication. Implementations with a higher tendency for leakage (e.g.,those with a relatively short housing and/or a relatively largeclearance between the plunger and the housing, as well as those in whicha relatively low viscosity fluid is pumped at relatively high pressures,as illustrated by FIGS. 4A and 4B) might have more discontinuities thanother implementations. Likewise, the discontinuities can have any of avariety of cross-sectional profiles, some of which may be moreappropriate under certain circumstances than others.

For example, FIG. 7A illustrates the side view of a plunger 700, whichhas been manufactured to incorporate discontinuities 704 a, 704 b, alongthe length of the plunger. In the embodiment illustrated by FIG. 7A, thediscontinuities 704 have a profile that generally can be described asV-shaped, exhibiting a progressive narrowing of the circumference of theplunger from a larger outside diameter D₂ to a smaller diameter D₃ asillustrated on FIG. 7B. Those skilled in the art will recognize,however, that in other circumstances difference cross-sectional profilesmay provide a more effective seal against excess leakage. For instance,FIG. 7C illustrates another plunger 708 having a single discontinuity712 with a square cross-sectional profile, such that, along the lengthof the plunger 708, the discontinuity 712 represents an abrupttransition from an outside diameter D₂ to a narrower diameter D₃. Thoseskilled in the art will also recognize that in still other embodimentsdiscontinuities having different cross-sectional profiles may beutilized, which can be, merely by way of example, U-shaped and/or thelike. The number of discontinuities is discretionary and can be variedin accordance with needs of particular implementations and/or as theresult of empirical testing under various circumstances.

In accordance with further embodiments of the invention, the end of theplunger that is placed into the plump chamber can include a variety ofdifferent faces (also described as “facial profiles”), irrespective ofthe composition of the plunger and/or housing. For example, as in theembodiment illustrated by FIGS. 3A and 3B, a plunger can have a flatface that describes a perpendicular angle with the length of theplunger. In other embodiments, however, the face of the plunger can beconvex, conical (i.e., pointed), etc. In still further embodiments, theface of the plunger can be concave, be notched and/or have any of avariety of cut-outs. In such embodiments, depending on the compositionof the ceramic comprising the plunger, the variation in the face profilecan allow for the deformation of part of the plunger, which, in somecases can serve to reduce the tolerance between the end of the plungerand the housing when substantial fluid pressure is applied to the faceof the plunger (as during pumping operations). While in the past,ceramic materials may have been considered too brittle and/or too rigidto permit such deformation on a consistent satisfactory basis,experimental testing has revealed that certain facial profiles, asdescribed herein, may be used with a variety of modern ceramicmaterials. (It should be noted, however, that embodiments of theinvention are not limited to ceramic materials.)

Deformation of the plunger in this way can, therefore, further reducethe amount of leakage of the pumped material along the length of theplunger. It should be noted that, while such plungers may be used in anyof the injector heads and/or pumps described above, the applications ofsuch plungers are not limited to such embodiments but may include anypump, especially those in which relatively high fluid pressures may beexpected, including without limitation centrifugal pumps, piston pumps,reciprocating plunger pumps, double-acting plunger pumps and/or thelike.

FIGS. 8A-8J illustrate several embodiments of plungers having faces ofvaried plunger face configurations, each of which can, in certaincircumstances allow for deformation of the end of the plunger. Forexample, FIG. 8A illustrates a plunger 800 including a notch 804. Across-sectional view of the plunger 800 and notch 804 is provided inFIG. 8B. In this exemplary embodiment, a high fluid pressure applied tothe face of plunger 800 (and, necessarily, to the surfaces of notch 804as well) can force either side of the plunger 800 to deform away fromthe notch 804, effectively increasing the cross-sectional diameter ofthe plunger 800 and thereby reducing the tolerance between the plungerand the housing.

In still other embodiments, for example, those illustrated in FIGS. 8Cand 8D, a plunger 808 can have a generally concave and/or hemisphericalface 812 (i.e., the facial profile can describe a generallyhemispherical opening). Merely by way of example, in some embodiments,the diameter of the hemispherical face may be approximately equal to thecross-sectional diameter of the plunger itself (such that, at its widestpoint, at or near the end portion of the plunger, the opening isapproximately as wide as the plunger itself. Alternatively, the openingmay be some fraction of the face; merely by way of example, the ratio ofthe opening's diameter to the cross-sectional diameter of the plungercan range from virtually 0 to nearly 1.0, depending on the material usedand the amount of deformation desired. FIGS. 8E and 8F show an exemplaryplunger 816 having a facial profile 820 defining a hemisphere, such thatthis ratio is approximately 0.8.

Another facial profile can define an opening that is generallycylindrical in shape. For instance, FIGS. 8G and 8H depict a plunger 808with such a facial profile. In some embodiments, the plunger can have adiameter of about one-quarter inch to about three inches, and inparticular between about three-eighths inch and about five-eighths inch;the cylindrical opening can be between about one-eighth inch and abouttwo inches in diameter. In particular embodiments, the plunger can havea diameter between about one-quarter inch and about one inch, and thecylindrical opening can have a diameter between about one-eighth inchand about three-eights inch. In other embodiments, the cylindricalopening can extend between about one-eighth inch and about two inchesinto the plunger, and in particular between about three-eighths inch andabout one and one-eighth inches.

Other facial profiles may be used as well. Merely by way of example, inparticular embodiments, (for example, the embodiment illustrated byFIGS. 81 and 8J) a plunger 832 can have with a “keyhole” cutout, suchthat the face of the plunger includes a relatively narrow opening 836that widens as it extends into the plunger 832 to describe a relativelylarger void 840 within the plunger. Such embodiments can be used, undersome circumstances, to cause deformation along a greater length of theend of plunger 832 and/or can be varied as desired to accomplish theintended deformation profile of the plunger 832.

The dimensions above represent values that have proven to be effectivein certain applications. Those skilled in the art should appreciate,however, that these values, which can be appropriate for certainimplementations, may be modified as appropriate in other circumstances,depending, for example, on the viscosity of the fluid being pumped, thesize of the plunger, the flow rate of the pump, and/or otherapplication-specific factors. Moreover, although the openings above havebeen described as cylindrical, hemispherical, etc. for ease ofdescription, other embodiments of the invention can feature differentvariations on these profiles. Merely by way of example, in someembodiments, it may be advantageous for a profile to be more or lessconcave than a true hemisphere (such that the opening describes half ofan ellipsoid). Likewise, a generally cylindrical opening may have aroughly cylindrical end, such that, for example, some embodiments mayfeature opening similar to that depicted by FIGS. 8G and 8H but with aclosed end approximating that of the opening depicted by FIGS. 8E and8F. Further, as noted above, a plunger might have a differentcross-sectional shape, and/or an opening might have a differentcross-sectional shape. Based on the disclosure herein, those skilled inthe art will recognize that other variations and modifications arepossible as well, without varying from the scope of the invention.

Turning now to FIG. 9, a chart 900 illustrates the leakage performanceof various facial profiles during the pumping of water, demonstratingsome of the performance advantages of various embodiments of theinvention. The tests illustrated by the chart 900 were all performedwith a piston pump having a plunger three-eighths inch in diameter witha housing length of 1.158 inches. It should be noted that, whilespecific leakage data may vary according to application, the relativeperformance enhancements of different facial profiles may be expected toremain fairly consistent, although certain profiles may be relativelymore advantageous under certain circumstances. As illustrated, theleakage of all facial profiles may be roughly equivalent at lowpressures. At higher pressures, however, it can be seen that a flatfacial profile (i.e., a plunger with no opening in its face) may exhibitrelatively large leakage (e.g., approximately 450 ml/hour at 6000 psi).In contrast, a plunger with a hemispherical facial profile (such as thatillustrated by FIGS. 8C and 8D), exhibits significantly less leakage atthe same pumping pressure (e.g., approximately 250 ml/hour at 6000 psi),and a plunger with a cylindrical facial profile exhibits even lessleakage. For instance, a plunger with a cylindrical opening one-quarterinch in diameter and one-half inch deep exhibits approximately 220ml/hour leakage at 6000 psi, and a plunger with a cylindrical openingone-quarter inch in diameter and one inch deep exhibits approximately200 ml/hour leakage at the same pressure.

It is believed that these varying facial profiles reduce pump leakage(also referred to as “blow by”) by deforming under the pressure of thefluid being pumped, thereby reducing the clearance between the plungerand the plunger housing, and consequently reducing the available areafor the fluid to flow between the plunger and the housing. In someembodiments, therefore, the plunger and housing may be configured sothat the opening extends into the portion of the plunger that remainswithin the housing even when the plunger is fully-extended, ensuringthat a deformed portion of the plunger remains within the housing at alltimes during operation.

Although the facial openings described herein can provide enhanceleakage performance when used with a wide variety of plungers and/orhousings, such openings are particularly advantageous when used withceramic plungers and/or housings (including without limitation plungersand/or housings comprising any of the materials described in detailabove), due to the relative rigidity and durability of ceramics overother materials, such as steel and other metals. Merely by way ofexample, ceramic plungers can tolerate relatively higher pressureswithout excessive deformation. In addition, the hardness of ceramicsallows such plungers and/or housings to have longer operating lives, asdescribed above, relative to their metal counterparts. Because thefacial openings reduce the clearance between the plunger and thehousing, this enhanced durability can be advantageous when such openingsare employed.

Those skilled in the art will recognize that embodiments of theinvention can include any of the face profiles described above, as wellas others. The choice of face profile can depend on the fluid pressureexhibited by the material being pumped as well as other qualities of thefluid and/or plunger, e.g., viscosity and/or Reynolds numbers of thefluid, length of the plunger housing, tolerance between plunger and thehousing, etc., as such characteristics are described above.

In some cases, a plunger (of whatever facial profile and/or composition)may be coupled with a thrust rod adaptor (and/or any other mechanism fordriving and/or axially displacing the plunger) via a coupling assembly,which can, in some embodiments, be a flexible coupling assembly. Aflexible coupling assembly can be used to allow a plunger to be drivenand/or displaced in a direction different than the direction of thedriving mechanism's movement. Further, a flexible coupling assembly maybe used to allow for acceptable operation of a pump even when theplunger is not perfectly aligned axially with the driving mechanism,providing a greater tolerance for misalignment than other couplingassemblies.

Merely by way of example, FIG. 10A illustrates a drive element 1000(which, in the exemplary illustration is a thrust rod but could also beany other suitable component) and a plunger 1020. The thrust rod 1000,which can be fashioned, machined, cast, etc. from any suitable material,including without limitation steel and/or other metals, ceramics, and/orthe like, can comprise a thrust rod body 1004 and a means for attachingthe thrust rod to a driving apparatus (such as a diaphragm motor, asdescribed above, or any other mechanism which can provide for movementof the thrust rod). Such means can include, for example, a couplingnotch 1008 or any other suitable attachment mechanism, such as clips,threaded adaptors, and/or the like. The thrust rod 1000 can alsocomprise a collar 1012, which can function to prevent a flexiblecoupling assembly (described in more detail below) from sliding alongthe length of the thrust rod 1000. The thrust rod 1000 can, in someembodiments, further feature recesses or other devices to allow for moresecure attachment of the coupling assembly to the thrust rod 1000. Inthe illustrated embodiment, for example, the thrust rod 1000 features anannular recess 1016, which can allow for the attachment of anappropriate clip, as described in detail below. Other embodiments mayinclude protrusions, slots (e.g., for the insertion of a cotter pin),flattened surfaces and/or the like, which also can facilitate theattachment of the coupling assembly to the thrust rod 1000. Likewise,the plunger 1020 (which can be, inter alia, any of the plungersdescribed elsewhere herein) may feature similar devices, such as theannular recess 1024, and/or a collar (not shown in FIG. 10A).

Turning now to FIG. 10B, the thrust rod 1000 and plunger 1020 of FIG.10A are shown coupled with a flexible coupling assembly, which includesa coupling member 1028 that is disposed over opposing ends of the rod1000 and plunger 1020. Further, one (or more) fastening devices 1032 aand 1032 b can be used to fasten the coupling member 1028 to the rod1000 and plunger 1020, respectively. Merely by way of example, inaccordance with some embodiments, a nine-sixteenths inch hose clamp,such as part no. 4E587 from W.W. Grainger, Inc. of Lake Forest, Ill.,may be used as a fastening device. As noted above, other fasteningdevices may be used as well. Alternatively, the coupling member 1028 maybe formed integrally with the thrust rod 1000 and/or the plunger 1020,which may obviate the need for one or more of the fastening devices.

As mentioned above, in accordance with certain embodiments, the couplingmember 1028 may be flexible. Merely by way of example, some embodimentsfeature a length of five-sixteenths inch (inner diameter) reinforced PVCtubing as a coupling member. (The size of the coupling member may dependon the size of the plunger.) Other, similar materials may be used aswell, depending on the application and the desired degree offlexibility. For example, steel tubing and/or tubing reinforced withKevlar, metallic cladding and/or sheathing, etc. may be used foradditional durability. This flexibility allows for the plunger 1020 tobe operated in a somewhat unaligned direction, relative to the axialdirection of the thrust rod 1000, as depicted by FIG. 10C. Thisflexibility also provides enhanced compatibility with ceramic plungersand/or housings, which may sometimes be relatively intolerant.

Another set of embodiments provides methods of producing and/or usingpumps and/or plungers. Merely by way of example, FIG. 11 illustrates amethod 1100 of producing/implementing pumps and plungers, in accordancewith some such embodiments. At block 1104, a plunger may be provided.The plunger may be constructed of any material, including, inter alia,the materials discussed above, and may feature any appropriate facialprofile, including, inter alia, the facial profiles discussed above. Inaccordance with some embodiments, providing a plunger can comprisemachining and/or otherwise modifying the plunger to describe anappropriate facial profile. Merely by way of example, a plunger with agenerally flat facial profile might be machined with a die having anappropriate shape to impart the desired facial profile. Alternativelyand/or in addition, a plunger may be cast/molded (and/or otherwiseformed) with a desired facial profile.

At block 1108, a drive element may be provided. The drive element cancomprise any of the components described above. For example, the driveelement can comprise a thrust rod (also described as a “thrusting rod”)or similar component. The plunger may be coupled with the drive element(block 1112) using any suitable method and/or mechanism. In someembodiments, coupling the plunger with the drive element can comprisecoupling the plunger and the drive element using a coupling assembly,including without limitation a flexible coupling assembly, someexemplary embodiments of which are described with respect to FIGS.10A-10C, above. If necessary, the drive element and the plunger may bealigned (block 1116), e.g., to ensure that the drive element properlydrives the plunger to pump a fluid when in operation. In some cases, itmay be necessary that the plunger and drive element be axially alignedwith a relatively high degree of precision, to ensure proper operation.In other cases, however, such as when a flexible coupling assembly isused for example, it may be possible to align the drive element and theplunger with a relative lower degree of precision. In fact, in somecases (again, for example, when using a flexible coupling assembly), thedrive element and the plunger need not be axially aligned but insteadmay have a degree of alignment offset, as discussed above.

The drive element may be connected with a drive mechanism (block 1120).As used in this section, the term drive mechanism should be understoodto mean any source that can provide movement of the drive element and/orplunger sufficient to operate the plunger in such a way as to pump afluid. Merely by way of example, any such movement source discussedabove (including without limitation a diaphragm motor, an electricmotor, an internal combustion engine, etc.) may be used as a drivemechanism to drive the drive element and/or plunger. Finally, the pumpmay be operated (block 1124), for instance by operating the drivemechanism to drive the drive element, and/or by extension, the plunger,thereby reciprocally moving the plunger in and out of (or within) a pumpchamber, which can allow for the pumping of fluids.

Based on the disclosure herein, one skilled in the art can appreciatethat the reciprocal motion of the plunger relative to the pump chamberoften will impose a pressure on the fluid within the pump chamber,thereby effecting the pumping of the fluid. Conversely, the fluid mayexert a corresponding pressure on the plunger, and in particular on thefacial profile of the plunger (block 1128). This pressure can cause thedeformation of at least a portion of the plunger (block 1132). Thenature of the deformation may depend on the shape of any opening definedby the facial profile of the plunger, as described above, and thedeformation may, in some cases, reduce the clearance (tolerance) betweenthe plunger and a housing surrounding the plunger. As described above,plunger pumps often exhibit leakage between the plunger and the housing(i.e., along the length of the plunger), and this reduction in clearancecan result in a reduced area through which the fluid may escape betweenthe plunger and the housing, thereby reducing the relative amount ofleakage along the length of the plunger (block 1136).

In this way, embodiments of the invention provide plungers, plungerassemblies, and pumps, as well as methods for producing and/orimplementing them. The description above identifies certain exemplaryembodiments for implementing the invention, but those skilled in the artwill recognize that many modifications and variations are possiblewithin the scope of the invention. The invention, therefore, is definedonly by the claims set forth below.

1. A plunger assembly for use in a pump, the plunger assemblycomprising: a plunger having an axis, a first end portion and a secondend portion, the first end portion being configured to be coupled with aflexible coupling assembly and the second end portion being configuredto be exposed to a pump chamber, such that a reciprocal motion of theplunger along the axis of the plunger can result in the pumping of afluid through the pump chamber; a drive element having an axis, thedrive element being configured for reciprocal motion along the axis ofthe drive element; and a flexible coupling assembly coupled with thefirst end portion of the plunger and further coupled with the driveelement, the flexible coupling assembly being configured to translatethe reciprocal motion of the drive element to the plunger, causing areciprocal motion of the plunger along the axis of the plunger.